High-resolution microwave ranging with homodyne transceiver using synthetic bandwidth signals

In this article, we study the short-range homodyne microwave transceiver processing the composite signal constructed from linear frequency-modulated chirps repeated with uniform increment of the carrier frequency. The ability of FMCW sensor to produce the chirp signal with high linearity of the frequency modulation in the whole bandwidth determines its range resolution. For many applications, the single chirp may be replaced with a stepped-frequency sequence of narrowband signals also known as a stepped-frequency pulse train. Analysis of the existing publications on processing of similar signals has demonstrated that although this technique is not targeted for short-range sensors, certain modifications of signal parameters and processing technique provide simple and effective way to implement reliable homodyne sensors capable to operate with the proposed composite wideband signals. The simplified synthetic bandwidth technique is capable to provide stable results in highly cluttered environment and sufficiently robust to the signal corruption and inaccuracies of the pulse train parameters. A validity of the proposed approach is confirmed by the easily reproducible experiment.